Assessment of cefiderocol disk diffusion versus broth microdilution results when tested against complex clinical isolates.

Carbapenem-resistant is a major global health concern due to its high prevalence and limited treatment options. Cefiderocol is the only novel Food and Drug Administration (FDA)-approved β-lactam agent for the salvage treatment of carbapenem-resistant infection. Currently, a commercial automated susceptibility testing panel of cefiderocol is unavailable. Both the preparation of iron-depleted cation-adjusted Mueller-Hinton broth and the performance of broth microdilution are cumbersome in routine microbiology laboratories. A disk diffusion method is convenient for cefiderocol antimicrobial susceptibility testing, but limited data are available specifically for clinical isolates. Moreover, the Clinical and Laboratory Standards Institute published revisions to the cefiderocol disk diffusion breakpoints in 2022. Hence, we evaluated the performance of cefiderocol disk diffusion compared with the reference BMD against clinical isolates, especially those with cefiderocol zone diameters ≤ 14 mm.